Only problem with mealworms is they are high in fat, and this isn't a balanced diet giving them all they need to reach their potential or not have problems later on. If it were me would get them some turkey/gamebird starter for your young turkeys and guinea. You won't have issues when they are...
@Ruler of the Roost You can have separate flocks that can be cohesive with enough room/free range. I would not brood them together, catering to their different needs and prevent imprinting.
@Ruler of the Roost When things are hatched/born their nature is to imprint/ learn from what they see and hear. Imagining themselves, mimicking as to what is around them whether it be good for them or not. Such as a mother duck raising a chick and as soon as chick is old enough, mother duck...
:welcome Not a good idea to brood them all together as they all have different needs among other things. They imprint on each other not knowing differences creating problems later as already been stated. Size is only one difference to be concerned with. Turkeys and Guinea have different...